/Engine/Source/Runtime/Engine/Public/AnimationRuntime.h
Get KeyIndices usingFFrameRate::AsFrameTimeto calculate the keys and alpha value
static void GetKeyIndicesFromTime ( int32 & OutKeyIndex1, int32 & OutKeyIndex2, float & OutAlpha, const double Time, const [FFrameRate](API\Runtime\Core\Misc\FFrameRate) & FrameRate, const int32 NumberOfKeys )